Surgical forceps

ABSTRACT

A forceps includes a pair of shafts each having a jaw member disposed at a distal end thereof. One (or both) of the shafts is moveable relative to the other about a pivot pin between a spaced-apart position and an approximated position to move the jaw members between an open position and a closed position. A knife assembly includes a knife blade mechanically keyed to the pivot pin and moveable between an initial position, wherein the knife blade is disposed within one of the jaw members, and an extended position, wherein the knife blade extends between the jaw members. An actuator arm(s) is mechanically keyed to the pivot pin and extends therefrom. The actuator arm(s) is moveable between an un-actuated position and an actuated position to rotate the pivot pin relative to the jaw members to move the knife blade between the initial position and the extended position.

BACKGROUND

The present disclosure relates to a surgical forceps and, moreparticularly, to a surgical forceps including replaceable jaw members.

TECHNICAL FIELD

A forceps is a plier-like instrument which relies on mechanical actionbetween its jaws to grasp, clamp and constrict vessels or tissue.Electrosurgical forceps utilize both mechanical clamping action andelectrical energy to affect hemostasis by heating tissue and bloodvessels to coagulate and/or cauterize tissue. Certain surgicalprocedures require more than simply cauterizing tissue and rely on theunique combination of clamping pressure, precise electrosurgical energycontrol and gap distance (i.e., distance between opposing jaw memberswhen closed about tissue) to “seal” tissue, vessels and certain vascularbundles. Typically, once a vessel is sealed, the surgeon has toaccurately sever the vessel along the newly formed tissue seal.Accordingly, many vessel sealing instruments have been designed whichincorporate a knife or blade member which effectively severs the tissueafter forming a tissue seal.

Generally, surgical instruments, including forceps, can be classified assingle-use instruments, e.g., instruments that are discarded after asingle use, partially-reusable instruments, e.g., instruments includingboth disposable portions and portions that are sterilizable for reuse,and completely reusable instruments, e.g., instruments that arecompletely sterilizable for repeated use. As can be appreciated, thoseinstruments (or components of instruments) that can be sterilized andreused help reduce the costs associated with the particular surgicalprocedure for which they are used. However, although reusable surgicalinstruments are cost-effective, it is important that these instrumentsbe capable of performing the same functions as their disposablecounterparts and that any disposable components of these instruments beefficiently removable and replaceable with new components.

SUMMARY

In accordance with one embodiment of the present disclosure, a forcepsis provided, the forceps includes a pair of shaft members each having ajaw member disposed at a distal end thereof. One (or both) of the shaftmembers is moveable relative to the other about a pivot pin between aspaced-apart position and a first approximated position to move the jawmembers between an open position and a closed position. A knife assemblyis also provided. The knife assembly includes a knife blade and one ormore actuator arms. The knife blade is mechanically keyed to the pivotpin and moveable between an initial position, wherein the knife blade isdisposed within one of the jaw members, and an extended position,wherein the knife blade extends between the jaw members. The actuatorarm(s) are likewise mechanically keyed to the pivot pin and extendtherefrom. The actuator arm(s) is moveable between an un-actuatedposition and an actuated position to rotate the pivot pin relative tothe jaw members to move the knife blade between the initial position andthe extended position.

In one embodiment, the actuator arms) is coupled to a spring at an endthereof. The spring is moveable between an at-rest position and anextended position to move the actuator arm(s) between the un-actuatedposition and the actuated position, e.g., to move the knife bladebetween the initial position and the extended position. Morespecifically, the spring may be configured to move from the at-restposition to the extended position upon movement of the shaft members toa second approximated position. Further, the spring may be engaged toone of the shaft members at an end thereof and to the actuator arm(s) atan opposite end thereof.

In another embodiment, a first cam slot is defined within one of theshaft members and a second cam slot is defined within the actuatorarm(s). A cam pin is disposed through each of the first and second camslots and is coupled to the distal end of the spring, such that, uponmovement of the shaft members to the second approximated position, thespring is moved from the at-rest position to the extended position totranslate the cam pin along the first and second cam slots, therebymoving the actuator arm(s) to the actuated position, thus moving theknife blade to the extended position. Further, the forceps may beconfigured such that, upon movement of the shaft members to the secondapproximated position, one of the shaft members contacts the spring andurges the spring to move from the at-rest position to the extendedposition.

In yet another embodiment, one (or both) of the jaw members includes ajaw frame fixedly engaged to the respective shaft member and adisposable jaw housing releasably engageable with the jaw frame.Additionally, a seal plate may be releasably engaged to the jaw housing.The seal plate may include a longitudinally-extending blade channeldefined therethrough. The blade channel is configured to permit passageof the knife blade therethrough upon movement of the knife blade fromthe initial position to the extended position. Further, the seal platemay be adapted to connect to a source of electrosurgical energy, e.g.,for energizing the seal plate.

In still another embodiment, the jaw housing includes one or moreengagement features configured to releasably engage a complementaryengagement feature (or features) defined within the jaw frame.

In still yet another embodiment, the shaft members, the pivot pin, andthe knife assembly are releasably engaged to one another, e.g., suchthat the shaft members, the pivot pin and the knife assembly may beassembled and disassembled by the user.

A method of assembling a forceps, e.g., the forceps according to any ofthe embodiments discussed above, is also provided in accordance with thepresent disclosure. The method includes providing a pair of shaftmembers, each shaft member having a jaw member disposed at a distal endthereof, providing a pivot pin including first and second mechanicalkeying features, and providing a knife assembly. The knife assemblyincludes a knife blade having a first complementary mechanical keyingfeature and one or more actuator arm(s) having a second complementarymechanical keying feature. The method further includes pivotablycoupling the pivot pin to the shaft members such that the shaft membersare movable between a spaced-apart position and a first approximatedposition to move the jaw members between an open position and a closedposition, engaging the first mechanical keying feature of the pivot pinwith the first complementary mechanical keying feature of the knifeblade, and engaging the second mechanically keying feature of the pivotpin with the second complementary mechanical keying feature of theactuator arm(s). As such, when the forceps is assembled as describedabove, movement of the actuator arm(s) from an un-actuated position toan actuated position may be effected to rotate the pivot pin relative tothe jaw members, thereby moving the knife blade from an initialposition, wherein the knife blade is disposed within one of the jawmembers, to an extended position, wherein the knife blade is extendedbetween the jaw members.

In one embodiment, one (or both) of the jaw members includes a jaw framefixedly engaged to the respective shaft member and a disposable jawhousing releasably engageable with the jaw frame. In such an embodiment,the method may further include releasably engaging the disposable jawhousing to the jaw frame.

In another embodiment, the method includes releasably engaging a sealplate to the jaw housing. Further, the seal plate may be connected to asource of electrosurgical energy, e.g., via an electrosurgical cable.

In yet another embodiment, the method includes coupling a proximal endof the actuator arm(s) to a proximal end of one of the shaft members.More specifically, a cam pin may be inserted through a first cam slotdefined within one of the shaft members and through a second cam slotdefined within the actuator arm(s) to couple the actuator arm(s) to theshaft member. Accordingly, upon movement of the shaft members to asecond approximated position, the cam pin is translated along the firstand second cam slots, thereby moving the actuator arm(s) from theun-actuated position to the actuated position, e.g., to move the knifeblade from the initial position to the extended position.

In still another embodiment, the method includes providing a springhaving a proximal end and a distal end, coupling the cam pin to thedistal end of the spring, and coupling the proximal end of the spring toa proximal end of one of the shaft members. The spring is configured formovement from an at-rest position to an extended position upon movementof the shaft members to the second approximated position to move theactuator arms) from the un-actuated position to the actuated position,e.g., to move the blade from the initial position to the extendedposition.

A method of assembling a jaw member is also provided in accordance withthe present disclosure. The jaw member to be assembled may be any of thejaw members discussed above, e.g., a jaw member including a jaw frame, ajaw housing, an insulator, and an electrically-conductive seal plate.The method includes positioning the seal plate about the insulator,slidably positioning the jaw housing about the seal plate and theinsulator such that the jaw housing, the seal plate, and the insulatorare retained in fixed relation relative to one another, and releasablyengaging the jaw housing to the jaw frame to retain the jaw housing, theseal plate, the insulator, and the jaw frame in fixed relation relativeto one another.

In one embodiment, jaw housing includes a track defined therein. Theseal plate includes a pair of wings configured to slidably engage thetrack of the jaw housing to secure the seal plate, the jaw housing, andthe insulator to one another.

In another embodiment, the insulator is formed partially (or entirely)from a resiliently compressible material. The insulator is configured tobe compressed from an initial state to a compressed state uponpositioning of the jaw housing about the seal plate and the insulator.As such, the biasing force acting of the insulator, e.g., biasing theinsulator back toward the initial state, frictionally retains the jawhousing, the seal plate, and the insulator in fixed relation relative toone another, once the jaw member is assembled.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1 is a front, perspective view of one embodiment of a forcepsprovided in accordance with the present disclosure wherein the forcepsis shown in an open position;

FIG. 2 is a front, perspective view of the forceps of FIG. 1 shown in aclosed position;

FIG. 3 is a greatly-enlarged, perspective view of the end effectorassembly of the forceps of FIG. 1;

FIG. 4 is a greatly-enlarged, perspective view of the end effectorassembly of the forceps of FIG. 1 showing a disposable componentpositioned for engagement with one of the jaw members of the endeffector assembly;

FIG. 5 is an exploded, perspective view of the disposable component ofone of the jaw members of the forceps of FIG. 1;

FIG. 6 is a front, perspective view of the disposable component of FIG.5, shown as assembled;

FIG. 7 is an exploded, perspective view of the disposable component ofthe other jaw member of the forceps of FIG. 1;

FIG. 8 is a front, perspective view of the disposable component of FIG.7, shown as assembled;

FIG. 9 is an exploded, perspective view of the forceps of FIG. 1;

FIG. 10 is a perspective, longitudinal, cross-sectional view of the endeffector assembly of the forceps of FIG. 1 showing the knife blade in aninitial position;

FIG. 11 is a side, longitudinal, cross-sectional view of the endeffector assembly of the forceps of FIG. 1 showing the knife blade in anextended position;

FIG. 12 is a side view of the forceps of FIG. 1 shown in the openposition;

FIG. 13A is a side view of the forceps of FIG. 1 shown in the closedposition, wherein the knife blade is in the initial position;

FIG. 13B is a transverse, cross-sectional view of the forceps of FIG. 1shown in the closed position, wherein the knife blade is in the initialposition;

FIG. 14A is a side view of the forceps of FIG. 1 shown in the closedposition, wherein the knife blade is in the extended position; and

FIG. 14B is a transverse, cross-sectional view of the forceps of FIG. 1shown in the closed position, wherein the knife blade is in the extendedposition.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described in detail withreference to the drawing figures wherein like reference numeralsidentify similar or identical elements. As used herein, the term“distal” refers to the portion that is being described which is furtherfrom a user, while the term “proximal” refers to the portion that isbeing described which is closer to a user.

Referring initially to FIGS. 1 and 2, a forceps 10 is shown includingtwo elongated shafts 12 a and 12 b each having a distal end 14 a and 14b and a proximal end 16 a and 16 b, respectively. An end effectorassembly 100 including opposing jaw members 110, 120, is attached todistal ends 14 a and 14 b of shafts 12 a and 12 b, respectively.Opposing jaw members 110 and 120 are pivotably connected about a pivotpin 150 and are moveable relative to one another between an openposition (FIG. 1) and a closed position (FIG. 2), upon movement of shaftmembers 12 a and 12 b between a spaced-apart position (FIG. 1) and afirst approximated position (FIG. 2), for grasping tissue therebetween.Further, each jaw member 110, 120 includes a disposable component 210,220, respectively, that is releasably engaged thereon. Although forceps10 is shown as an open surgical forceps, jaw members 110, 120 includingdisposable components 210, 220, respectively, may similarly beconfigured for use with an endoscopic surgical forceps (not shown).

With continued reference to FIGS. 1 and 2, each shaft 12 a and 12 bincludes a handle 17 a and 17 b disposed at the proximal end 16 a and 16b thereof. Each handle 17 a and 17 b defines a finger hole 18 a and 18 btherethrough for receiving a finger of the user. As can be appreciated,finger holes 18 a and 18 b facilitate movement of shafts 12 a and 12 brelative to one another which, in turn, pivots jaw members 110 and 120between the open position (FIG. 1) and the closed position (FIG. 2),wherein the jaw members 110 and 120 cooperate to grasp tissuetherebetween. Further, as will be described in greater detail below,shafts 12 a, 12 b are moveable between a spaced-apart position (FIG. 1),a first approximated position for closing jaw members 110, 120 to grasptissue therebetween (FIG. 2), and a second approximated position foradvancing knife blade 261 of knife assembly 260 (FIGS. 9-11) between jawmembers 110, 120 to cut tissue grasped therebetween (FIGS. 14A-14B).

A ratchet 30 may be included for selectively locking jaw members 110,120 relative to one another at various positions during pivoting. Theratchet 30 may include graduations or other visual markings that enablethe user to easily and quickly ascertain and control the amount ofclosure force between the jaw members 110 and 120.

Turning now to FIGS. 3-4, in conjunction with FIGS. 1 and 2, and asmentioned above, forceps 10 includes a pair of jaw members 110, 120. Jawmembers 110, 120 each include a disposable component 210, 220 that isreleasably engageable with a jaw frame 112, 122, respectively. Jawframes 112, 122 of jaw members 110, 120, respectively, are fixedlyengaged to the respective shafts 12 a, 12 b, e.g., each jaw frame 112,122 is formed as a single component with the respective shaft 12 a, 12b. Disposable components 210, 220, are removeable from jaw frames 112,122, respectively, and are replaceable with new disposable components210, 220, e.g., disposable components are configured to be discarded andreplaced after a single use (or a single procedure), while shafts 12 a,12 b and their respective jaw frames 112, 122, are formed from asterilizable material, e.g., stainless steel, such that they may besterilized, e.g., placed in an autoclave, after each procedure forrepeated use. As will be described in greater detail below, forceps 10further includes a disposable knife assembly 260 (see FIG. 9) that isreleasably engageable therewith (although knife assembly 260 mayalternatively be configured as a sterilizable and, thus, reusablecomponent). As can be appreciated, requiring only a new set ofdisposable components 210, 220 and knife assembly 260 (FIG. 9), ratherthan an entire new surgical instrument, helps reduce the equipment costsassociated with performing a particular surgical procedure.

With reference now to FIGS. 5-6, disposable component 210 of jaw member110 will be described. Disposable component 210 generally includes aninsulative jaw housing 211, an insulator 215, and anelectrically-conductive tissue sealing plate 219. Jaw housing 211defines a generally horseshoe or U-shaped configuration forming anelongated aperture 214 extending longitudinally at least partiallytherethrough. As will be described in greater detail below, knife blade261 of knife assembly 260 (FIGS. 9-10) is configured for positioningwithin elongated aperture 214 of jaw housing 211 when in an initialposition. Knife blade 261 (FIGS. 9-10) is moveable from the initialposition within jaw housing 211 to an extended position, wherein knifeblade 261 extends between jaw members 110, 120 to cut tissue graspedtherebetween. Jaw housing 211 is further configured to mechanicallyengage insulator 215 and tissue sealing plate 219, e.g., in slidablesnap-fit engagement therewith, although other mechanisms (not shown) forreleasably securing jaw housing 211 about insulator 215 and tissuesealing plate 219 may be provided. The assembly of the disposablecomponents 210, 220 of jaw members 110, 120, respectively, will bedescribed in greater detail below.

Continuing with reference to FIGS. 5-6, jaw housing 211 includes one ormore engagement features, e.g., flexible, snap-fit protrusions 212,extending therefrom and configured to releasably engage jaw housing 211to jaw frame 112 of jaw member 110 (see FIG. 10). More specifically,flexible, snap-fit protrusions 212 of jaw housing 211 are configured forinsertion through complementary-shaped apertures 113 defined within jawframe 112 (see FIG. 10) such that jaw housing 211 may be releasablysecured to jaw frame 112. Further, protrusions 212 disposed on jawhousing 211 may be longitudinally and laterally offset relative to oneanother such that tilting, rotating, or other movement of disposablecomponent 210 relative to jaw frame 112 is substantially inhibited oncedisposable component 210 is engaged to jaw frame 112.

Jaw frame 112, as best shown in FIGS. 13B and 14B, and as will bedescribed in greater detail below, may include a blade slot 116 definedtherein and extending longitudinally therealong. Blade slot 116 isconfigured to align with elongated aperture 214 of jaw housing 211 uponengagement of jaw housing 211 to jaw frame 112 and is similarlyconfigured to permit positioning of knife blade 261 of knife assembly260 therein when knife blade 261 is disposed in the initial position.Accordingly, when knife blade 261 is moved from the initial position tothe extended position, knife blade 261 extends through blade slot 116 ofjaw frame 112 and through elongated aperture 214 of jaw housing 211 suchthat knife blade 261 is extended between jaw members 110, 120 to cuttissue grasped therebetween.

During assembly, as best shown in FIGS. 5-6 and 10, flexible, snap-fitprotrusions 212 of jaw housing 211 are aligned with apertures 113 of jawframe 112. Next, jaw housing 211 and jaw frame 112 are approximatedrelative to one another until tabs 213 disposed on the free ends offlexible, snap-fit protrusions 212 of jaw housing 211 snap intoengagement with notches 114 defined within the interior surfaces ofapertures 113 of jaw frame 112. An audible and/or tactile “snap,” orother feedback signal, may be provided to alert the user that jawhousing 211 has been securely engaged within jaw frame 112.

In order to disengage jaw housing 211 from jaw frame 112, jaw housing211 and jaw frame 112 are pulled apart from one another with sufficientforce such that tabs 213 of flexible snap-fit protrusions 212 of jawhousing 211 are disengaged from notches 114 of apertures 113 of jawframe 112, allowing jaw housing 211 to be removed from jaw frame 112.Similarly as described above, an audible and/or tactile “snap,” or otherfeedback signal, may alert the user that jaw housing 211 has beendisengaged from jaw frame 112.

Referring once again to FIGS. 5-6, insulator 215 is formed at leastpartially from an electrically-insulative material and is configured toelectrically isolate tissue sealing plate 219 from the remainingcomponents of jaw member 110. Insulator 215 is slidably disposablewithin jaw housing 211 and is configured to mechanically engage tissuesealing plate 219 thereon. Similar to jaw frame 112 and jaw housing 211,insulator 215 also includes a blade channel 216 extending longitudinallytherethrough to permit passage of knife blade 261 (see FIGS. 13B and14B). Proximal base 217 of insulator 215 is configured to abut theproximal end of tissue sealing plate 219 to retain tissue sealing plate219 in position within jaw housing 211 once insulator 215 and tissuesealing plate 219 have been slidably engaged therein. Additionally,insulator 215 may be formed at least partially from a compressiblematerial, e.g., silicon, that is compressed upon insertion of insulator215 into jaw housing 211 such that insulator 215 and tissue sealingplate 219 may be frictionally retained within jaw housing 211.

Electrically-conductive tissue sealing plate 219, as mentioned above, isdisposed about insulator 215. Tissue sealing plate 219 includes alateral flange 231 extending therefrom that is configured toelectrically connect tissue sealing plate 219 to a source ofelectrosurgical energy such as an electrosurgical generator (not shown),e.g., via an electrosurgical cable (not shown). As will be described ingreater detail below, disposable component 220 of jaw member 120 maysimilarly include an electrically-conductive tissue sealing plate 229(see FIGS. 7-8) such that electrosurgical energy may be selectivelysupplied to either or both of the electrically conductive tissue sealingplates 219, 229 of disposable components 210, 220 of jaw members 110,120, respectively, to seal tissue grasped between jaw members 110 and120. Further, either (or both) of tissue sealing plates 219, 229 mayinclude lateral flanges 231, 233, respectively, configured to connecttissue sealing plates 219, 229 to a source of energy to supply energythereto. Alternatively, other suitable mechanisms (not shown) forelectrically coupling tissue sealing plates 219, 229 to a source ofenergy may be provided.

With continued reference to FIGS. 5-6, tissue sealing plate 219 ofdisposable component 210 of jaw member 110 may include alongitudinally-extending blade channel 235 defined therein. Bladechannel 235 is configured to align with blade channel 216 defined withininsulator 215, elongated aperture 214 defined within jaw housing 211,and blade slot 116 defined within jaw frame 112 to permit passage ofknife blade 261 of knife assembly 260 (see FIGS. 13B and 14B)therethrough upon movement of knife blade 261 from the initial position(FIG. 13A) to the extended position (FIG. 13B). Blade channel 235 mayfurther be configured to facilitate and/or enhance cutting of tissueupon extension of knife blade 261 therethrough.

Continuing with reference to FIGS. 5-6, disposable component 210 of jawmember 110 may come preassembled, e.g., jaw housing 211, insulator 215and tissue sealing plate 219 may be engaged to one another duringmanufacturing, or may be configured to be assembled by the user. Ineither embodiment, disposable component 210 and/or the sub-componentsthereof (e.g., jaw housing 211, insulator 215 and/or tissue sealingplate 219) may define various configurations such that the user mayselect a particular disposable component 210 (or sub-component thereof)suitable for the particular surgical procedure to be performed. Forexample, different disposable components 210 (or the subcomponentsthereof) may be configured to define various dimensions, may be formedfrom various materials, and/or may have various other features tofacilitate mechanical, electrical, or frictional tissue dissectionand/or tissue sealing of a wide range of tissue sizes and compositions.Other variations are also contemplated. Put more generally, theinterchangeability of different disposable components 210 configured foruse with forceps 10 permits the user to customize forceps 10 for use ina wide-range of surgical procedures by selecting a particular disposablecomponent 210 (or subcomponent thereof) suitable for the particularsurgical procedure. As can be appreciated, such a configuration reducesthe overall number of different surgical instruments needed to perform awide-range of surgical procedures, thereby helping to reduce overallequipment costs, which, in turn, helps reduce the costs associated witheach surgical procedure.

Turning now to FIGS. 7-8, disposable component 220 of jaw member 120will be described. Disposable component 220 of jaw member 120 is similarto disposable component 210 of jaw member 110 and includes an insulativejaw housing 221, an insulator 225, and a tissue sealing plate 229. Jawhousing 221 is configured to mechanically engage insulator 225 andtissue sealing plate 229 in slidable snap-fit engagement therewith,although other mechanisms (not shown) are contemplated. Similar to jawhousing 211, jaw housing 221 includes one or more flexible, snap-fitprotrusions 222 configured to releasably engage jaw housing 221 to jawframe 122 of jaw member 120 (see FIG. 10). An audible and/or tactile“snap,” or other feedback signal, may be provided to alert the user asto the engagement (or disengagement) of jaw housing 221 and jaw frame122.

With continued reference to FIGS. 7-8, insulator 225 is similar toinsulator 215 of disposable component 210 of jaw member 110 (see FIGS.5-6) and is formed at least partially from an electrically-insulativematerial that is configured to electrically isolate tissue sealing plate229 from the remaining components of jaw member 120. Insulator 225 isslidably disposable within jaw housing 221 and is configured tomechanically engage tissue sealing plate 229 thereon. When disposablecomponent 220 is assembled, proximal base 227 of insulator 225 abuts theproximal end of tissue sealing plate 229 to retain tissue sealing plate229 in position within jaw housing 221. Similarly as discussed abovewith regard to disposable component 210 (FIGS. 5-6), insulator 225 maybe formed at least partially from a compressible material, e.g.,silicon, such that insulator 225 and tissue sealing plate 229 may befrictionally retained within jaw housing 221.

As shown in FIGS. 7-8, tissue sealing plate 229 is configured to sitatop insulator 225 and to mechanically engage jaw housing 221. Morespecifically, with tissue sealing plate 229 disposed about insulator225, insulator 225 and tissue sealing plate 229 may be slidablypositioned within jaw housing 221. Upon slidable positioning ofinsulator 225 and tissue sealing plate 229 within jaw housing 221,proximal base 227 of insulator 225 may be configured to snap-fittinglyengage jaw housing 221 to securely retain insulator 225 within jawhousing 221, while proximal base 227 of insulator 225 abuts the proximalend of tissue sealing plate 229 to retain tissue sealing plate 229 inposition within jaw housing 221. Additionally, insulator 225 may beformed at least partially from a compressible material to frictionallyengage jaw housing 221, insulator 225 and tissue sealing plate 229 ofdisposable component 220 to one another.

Tissue sealing plate 229 may further include a longitudinally-extendingblade channel 237 defined at least partially therethrough that permitsextension of knife blade 261 of knife assembly 260 therethrough (seeFIG. 10) upon extension of knife blade 261 to the extended position.Blade channel 237 may be configured to facilitate and/or enhance cuttingof tissue during extension of knife blade 261 therethrough (FIG. 10). Asdiscussed above, tissue sealing plate 229 may also include a lateralflange 233 adapted to connect tissue sealing plate 229 to a source ofelectrosurgical energy for energizing tissue sealing plates 219, 229 ofjaw members 110, 120, respectively.

Jaw housing 221, insulator 225, and/or tissue sealing plate 229 mayotherwise be configured similarly to jaw housing 211, insulator 215, andtissue sealing plate 219, respectively, of disposable component 210 ofjaw member 110, discussed above (see FIGS. 5A-5C). Further, although jawframe 112 and disposable component 210 are shown configured to retainknife blade 261 of knife assembly 260 (FIGS. 9-10) therein when knifeblade 261 is disposed in the initial position, this configuration may bereversed, e.g., such that jaw frame 122 and disposable component 220 ofjaw member 120 are configured to retain knife blade 261 of knifeassembly 260 therein (FIGS. 9-10).

Similar to disposable component 210, discussed above, disposablecomponent 220 may come preassembled, e.g., disposable component 220 maybe assembled during manufacturing, or may be configured to be assembledby the user. In either embodiment, similarly as discussed above,disposable component 220 and/or the sub-components thereof (e.g., jawhousing 221, insulator 225 and/or tissue sealing plate 229) may definevarious configurations such that the user may select a particulardisposable component 220 (or sub-component thereof) suitable for theparticular surgical procedure to be performed.

Turning now to FIGS. 9-11, in conjunction with FIGS. 1 and 2, knifeassembly 260 will be described. Knife assembly 260 is configured forreleasable coupling to forceps 10 such that a user may assemble,disassemble, and reassemble forceps 10, e.g., to sterilize the reusableportions and replace the disposable portions of forceps 10 inpreparation for reuse of forceps 10. However, forceps 10, includingknife assembly 260, may also be configured as a fully-assembledinstrument, e.g., where forceps 10 is permanently assembled at the timeof manufacturing.

As best shown in FIG. 9, knife assembly 260 generally includes a knifeblade 261, one or more actuator arms 262, e.g., two actuator arms 262,and a spring-cam mechanism 280 (FIGS. 1-2). As shown in FIG. 9, knifeassembly 260 includes two actuator arms 262 positioned on either side ofshaft 12 a, although only one actuator arm 262 need be provided.Actuator arms 262 are coupled to knife blade 261 via pivot pin 150, suchthat, as will be described in greater detail below, movement of actuatorarms 262 between an un-actuated position (FIG. 13A) and an actuatedposition (FIG. 14A) rotates pivot pin 150 relative to jaw members 110,120 to move knife blade 261 between the initial position (FIG. 13B) andthe extended position (FIG. 14B).

Referring again to FIGS. 9-11, in conjunction with FIGS. 1 and 2,actuator arms 262 extend proximally from pivot pin 150 along shaft 12 a(although actuator arms 262 may alternatively be configured to extendalong shaft 12 b). More specifically, each actuator arm 262 includes adistal aperture 268 defined therein for engaging pivot pin 150therethrough. As best shown in FIG. 12, pivot pin 150 and actuator arms262 each define complementary mechanical keying features, e.g., notches152 and protrusions 269, respectively, configured to engage one anothersuch that rotation of actuator arms 262 about pivot pin 150 effectssimilar rotation of pivot pin 150 relative to jaw members 110, 120 ofend effector assembly 100. As shown in the Figures, pivot pin 150includes notches 152 defined within an outer peripheral surface thereof,each notch 152 is configured for engaging a complementary-shapedprotrusion 269 of each actuator arm 262, which extend inwardly intodistal apertures 268 of actuator arms 262. However, the number, size,shape and/or configuration of the complementary mechanical keyingfeatures of pivot pin 150 and actuator arms 262 may be varied so long aspivot pin 150 and actuator arms 262 are engaged to one another such thatrotation of actuator arms 262 about pivot pin 150 effects similarrotation of pivot pin 150 relative to jaw members 110, 120 of endeffector assembly 100.

With continued reference to FIGS. 9-11, and in particular to FIG. 9,knife blade 261 of knife assembly 260 likewise includes a mechanicalkeying feature, e.g., protrusion 264, extending into a proximal aperture263 thereof for engaging a complementary mechanical keying feature,e.g., notch 154, of pivot pin 150 upon insertion of pivot pin 150through proximal aperture 263 of knife blade 261. Similarly as discussedabove, due to the mechanically-keyed engagement between protrusion 264of knife blade 261 and notch 154 of pivot pin 150, rotation of pivot pin150 relative to jaw members 110, 120 effects similar rotation of knifeblade 261 about pivot pin 150. As such, with actuator arms 262 and pivotpin 150 mechanically-keyed to one another, and with pivot pin 150 andknife blade 261 mechanically-keyed to one another, actuator arms 262 maybe rotated about pivot pin 150, e.g., between the un-actuated position(FIG. 13A) and the actuated position (FIG. 14A), to rotate knife blade261 about pivot pin 150 and relative to jaw members 110, 120, e.g.,between the initial position (FIG. 13B) and the extended position (FIG.14B). As will be described in greater detail below, during assembly,actuator arms 262 and knife blade 261 are configured to be engaged topivot pin 150 such that the initial position of knife blade 261, e.g.,wherein knife blade 261 is disposed within jaw member 110, correspondsto the un-actuated position of actuator arms 262.

Referring momentarily to FIGS. 1-2, although pivot pin 150 is configuredto engage knife blade 261 and actuator arms 262 of knife assembly 260 inmechanically-keyed engagement, pivot pin 150 need not bemechanically-keyed to shafts 12 a, 12 b. In other words, shafts 12 a and12 b are free to pivot relative to one another about and relative topivot pin 150 between the spaced-apart position and the firstapproximated position for moving jaw members 110, 120 between the openand closed positions for grasping tissue therebetween, while knife blade261 and actuator arms 262 of knife assembly 260 remain disposed in theinitial and un-actuated positions, respectively. As will be described ingreater detail below, shafts 12 a, 12 b may then be moved to the secondapproximated position to move actuator arms 262 to the actuated positionto rotate pivot pin 150 relative to jaw members 110, 120 and to therebymove knife blade 261 from the initial position to the extended positionto cut tissue grasped between jaw members 110, 120. Alternatively, pivotpin 150 may be mechanically-keyed to one or both of jaw members 110, 120such that moving shafts 12 a, 12 b between the spaced-apart andapproximated positions closes jaw members 110, 120 to grasp tissue and,thereafter, extends knife blade 261 therebetween to cut tissue.

Turning once again to FIGS. 9-11, in conjunction with FIGS. 1-2,actuator arms 262 of knife assembly 260 each define an angled proximalportion 265 that includes an angled cam slot 266 defined therein andextending therealong. Further, one of the shafts, e.g., shaft 12 a,includes a pair of substantially parallel cam slots 13 a defined thereinand extending longitudinally therealong adjacent to cam slots 266 ofactuator arms 262. More particularly, cam slots 13 a of shaft 12 a aremisaligned, or angled relative to cam slots 266 of actuator arms 262such that the respective cam slots 13 a, 266 intersect one another at anintersection position 285 (see FIGS. 13A and 14A).

Continuing with reference to FIGS. 1-2 and 9-11, knife assembly 260further includes a leaf spring 281, or other biasing member, defining anarch-shaped configuration when at-rest. Proximal end 283 of leaf spring281 is engaged to shaft 12 a and arches therefrom toward shaft 12 bbefore arching back toward shaft 12 a to distal end 282 of leaf spring281. Distal end 282 of leaf spring 281 is coupled to a cam pin 284 thatis removably engageable within cam slots 13 a, 266, of shaft 12 a andactuator arms 262, respectively. As can be appreciated, with cam pin 284disposed through both cam slots 13 a of shaft 12 a and cam slots 266 ofactuator arms 262, the position of cam pin 284 corresponds to theintersection position 285 of shaft 12 a and actuator arms 262.

Initially, as shown in FIGS. 1-2 and FIG. 13A, cam pin 284 is retainedat proximal ends 15 a, 267 of cam slots 13 a, 266, respectively, underthe bias of leaf spring 281. In this position, actuator arms 262 aredisposed in the un-actuated position. As will be described in greaterdetail below, as leaf spring 281 is urged from the arched-configurationtoward a relatively linear configuration, e.g., upon movement of shafts12 a, 12 b to the second approximated position (FIG. 14A), distal end282 of leaf spring 281 is urged distally along shaft 12 a such that campin 284 is translated along cam slots 13 a, 266 of shaft 12 a andactuator arms 262, respectively. As such, due to the angledconfiguration of cam slot 266 of actuator arms 262 relative to cam slots13 a of shaft 12 a, translation of cam pin 284 along cam slots 13 a,266, of shaft 12 a and actuator arms 262, respectively, urges actuatorarms 262 to rotate about pivot pin 150 and relative to shaft member 12 afrom the un-actuated position toward the actuated position (see FIG.14A).

Referring now to FIGS. 1-11, the assembly of forceps 10 will bedescribed. As mentioned above, forceps 10 may be configured to beassembled, disassembled, and reassembled by the user. More particularly,forceps 10 may be configured such that shafts 12 a, 12 b aresterilizable and reusable, while the remaining components of forceps 10are disposable after a single use (although some of these components mayalso be configured as reusable components). Accordingly, since the useris required to discard the old components, sterilize or otherwiseprepare the reusable components for reuse, and reload forceps 10 withnew disposable components, forceps 10 is configured to be readilyassembled and disassembled by a user, as will become more apparent inview of the following. Further, although the follow description bynecessity recites the assembly steps of forceps 10 in a particularorder, it is envisioned that the following assembly steps of forceps 10be performed in any suitable order.

With continued reference to FIGS. 1-11, and with reference to FIG. 9 inparticular, in order to assemble forceps 10, proximal end 283 of leafspring 281 is engaged with shaft 12 a toward proximal end 16 a thereof.More particularly, proximal end 283 of leaf spring 281 may befrictionally engaged within a recess (not explicitly shown) definedbetween proximal end 16 a of shaft 12 a and handle 17 a or may besecured to shaft 12 a in any other suitable fashion such that proximalend 283 of leaf spring 281 is releasably engageable in a fixed positionrelative to shaft 12 a.

Next, cam pin 284 is coupled to distal end 282 of leaf spring 281, e.g.,cam pin 284 is inserted through an aperture 286 defined within distalend 282 of leaf spring 281, and is inserted through cam slots 13 a, 266,of shaft 12 a and actuator arms 262, respectively. Any suitableengagement mechanism (not shown) for securing cam pin 284 withinaperture 286 and cam slots 13 a, 266 may be provided, e.g., end caps(not shown) may be releasably positioned on opposite ends of cam pin284.

Next, pivot pin 150 is inserted into position. In order to pivotablyengage pivot pin 150 within apertures 19 a, 19 b, of shafts 12 a, 12 b,respectively, and to mechanically-key pivot pin 150 in engagement withactuator arms 262 and knife blade 261, distal apertures 268 of actuatorarms 262, proximal aperture 262 of knife blade 261 and apertures 19 a,19 b of shafts 12 a, 12 b, respectively, are aligned with one anotherwith knife blade 261 of knife assembly 260 disposed within jaw member110 in the initial position, as discussed above. Next, pivot pin 150 isinserted through the aligned apertures.

More specifically, pivot pin 150 is first inserted through aperture 19 bof shaft 12 b. Next, pivot pin 150 is inserted through proximal aperture263 of knife blade 261 such that the complementary mechanical keyingfeatures thereof engage one another. Pivot pin 150 is thereafteradvanced through aperture 19 a of shaft 12 a. Finally, actuator arms 262are positioned about pivot pin 150 on opposite sides thereof such thatactuator arms 262 and pivot pin 150 are engaged in a mechanically-keyedrelation relative to one another, as discussed above.

The different mechanical keying features of pivot pin 150 correspondingto knife blade 261 and actuator arms 262 are positioned relative to oneanother such that, upon assembly of forceps 10, knife blade 261 isinitially disposed in the initial position, and such that actuator arms262 are initially disposed in the un-actuated position, both under thebias of leaf spring 281 (which is disposed in the at-rest, or archedposition). Visual markings or other indicia (not shown) may be providedto ensure the proper orientation and/or position of knife blade 261 andactuator arms 262 relative to pivot pin 150 and relative to each othersuch that this initial position is achieved upon assembly of forceps 10.Alternatively, or additionally, the mechanical keying features ofactuator arms 262, knife blade 261, and/or pivot pin 150 may beconfigured such that pivot pin 150 may only be engaged with knife blade261 and/or actuator arms 262 in the proper initial orientation andposition, thereby helping to ensure proper assembly of forceps 10.

With reference to FIGS. 5-6, the assembly of disposable component 210 ofjaw member 110 will be described. As discussed above, disposablecomponent 210 generally includes insulative jaw housing 211, insulator215, and electrically-conductive tissue sealing plate 219. First, asbest shown in FIG. 5, tissue sealing plate 219 is positioned oninsulator 215. More particularly, tissue sealing plate 219 is positionedon top of insulator 215 longitudinally between proximal base 217 ofinsulator 215 and distal lip 218 of insulator 215 and such that lateralwings 232 of tissue sealing plate 219 surround the longitudinal sides ofinsulator 215. As such, tissue sealing plate 219 and insulator 215 areretained in fixed longitudinal position relative to one another viaproximal base 217 and distal lip 218 and are retained in fixed lateralposition relative to one another via lateral wings 232 of tissue sealingplate 219.

With tissue sealing plate 219 disposed about insulator 215, as describedabove, tissue sealing plate 219 and insulator 215 are slidably engagedwithin jaw housing 211. More particularly, tissue sealing plate 219 andinsulator 215 are slid distally into engagement with track 238 definedwithin jaw housing 211 from the proximal end of jaw housing 211 to thedistal end of jaw housing 211 until tissue sealing plate 219 andinsulator 215 are substantially fully disposed within jaw housing 211.Upon insertion of tissue sealing plate 219 and insulator 215, distal lip218 of insulator 215 may be configured to engage an interior surface oftrack 238, while proximal base 217, as mentioned above, may beconfigured to snap-fittingly engage jaw housing 211. Further, in thisconfiguration, tissue sealing plate 219 is inhibited from being lifted,or disengaged from jaw housing 211 via the engagement of lateral wings232 within track 238 of jaw housing 211. In other words, jaw housing 211secures insulator 215 and tissue sealing plate 219 therein.Additionally, or alternatively, as mentioned above, insulator 215 may beformed from a resiliently compressible material that is compressed,e.g., from an initial state to a compressed state, in order to allowinsulator 215 and tissue sealing plate 219 to be slidably insertedthrough track 238 of jaw housing 211. Accordingly, once insulator 215and tissue sealing plate 219 are disposed within jaw housing 211,insulator 215, tissue sealing plate 219, and jaw housing 211 arefrictionally secured to one another under the bias of insulator 215,e.g., as insulator 215 attempts to resiliently returned to the initial,non-compressed state.

Referring now to FIGS. 7-8, disposable component 220 of jaw member 120is assembled similarly to disposable component 210 of jaw member 110.More particularly, tissue sealing plate 229 is first positioned on topof insulator 225 between proximal base 227 and distal lip 228 ofinsulator 225 and such that lateral wings 236 of tissue sealing plate229 surround the longitudinal sides of insulator 225. Next, tissuesealing plate 229 and insulator 225 are slid distally into engagementwith track 239 defined within jaw housing 221 until tissue sealing plate229 and insulator 225 are disposed within jaw housing 221. Oncepositioned within jaw housing 221, distal lip 228 of insulator 225 maybe configured to engage an interior surface of track 239 and/or proximalbase 227 of insulator 225 may be configured to snap-fittingly engage jawhousing 221, while lateral wings 236 of tissue sealing plate 229 areengaged within track 239 of jaw housing 221. Additionally, oralternatively, as mentioned above, insulator 225 may be formed from aresiliently compressible material to further secure the components ofdisposable component 220 to one another.

As can be appreciated, the above-described configuration of disposablecomponents 210, 220 of jaw members 110, 120, respectively, obviates theneed to overmold, machine, or otherwise form the components of jawmembers 110, 120 to one another, thus allowing an end user to assembleand disassemble jaw members 110, 120 without the need for specializedequipment.

With disposable components 210, 220 of jaw members 110, 120 fullyassembled, as described above, disposable components 210, 220 may besnap-fittingly engaged to their respective jaw frames 112, 122, tocomplete the assembly of forceps 10. Alternatively, either (or both) ofthe jaw housings 211, 221 may be configured for slidable positioningabout the respective insulator 215, 225 and tissue sealing plate 219,229, as well as the respective jaw frame 112, 122, to secure therespective disposable component 210, 220 to the corresponding jaw frame112, 122 (as opposed to the snap-fitting arrangement discussed above).In other words, the insulators 215, 225 and tissue seal plates 219, 229may first be positioned on the jaw frames 112, 122, respectively, withthe respective jaw housing 211, 221 subsequently slide-fit thereabout tosecure the respective insulators 215, 225, tissue sealing plates 219,229, and jaw frames 112, 122 of each jaw member 110, 120 to one another.

Turning now to FIGS. 12-14B, the use and operation of forceps 10 will bedescribed. Initially, the reusable portion(s) of forceps 10, e.g.,shafts 12 a, 12 b, are sterilized and/or otherwise prepared for use (orreuse). Next, forceps 10 is assembled as described above. At this point(or prior to), an electrosurgical energy source (not shown) may becoupled to tissue sealing plate 219 and/or tissue sealing plate 229 ofjaw members 110, 120, respectively, e.g., via an electrosurgical cable(not shown) coupled at a first end to the energy source (not shown) andat a second end to lateral flange 231 and/or lateral flange 233 oftissue sealing plates 219, 229, respectively (see FIGS. 5-8). However,the electrical connection(s) may alternatively be configured to runthrough either of shafts 12 a, 12 b, or may otherwise be configured tosupply energy to tissue sealing plates 219, 229 via any other suitablemechanism. With forceps 10 fully assembled (and with the electricalconnections intact), forceps 10 is ready for use.

Referring to FIG. 12, shafts 12 a and 12 b are moved to the spaced-apartposition such that jaw members 110, 120, disposed at distal ends 14 a,14 b, of shafts 12 a and 12 b, respectively, are moved to the openposition. At this point, leaf spring 281 is disposed in the at-restposition, cam pin 284 is disposed at the proximal ends 15 a, 267 of camslots 13 a, 266, respectively, actuator arms 262 are disposed in theun-actuated position, and knife blade 261 is disposed in the initialposition. With jaw members 110, 120 disposed in the open position, asshown in FIG. 12, forceps 10 may be manipulated into position such thattissue to be grasped, sealed and/or divided is disposed between jawmembers 110, 120.

Once tissue is positioned as desired, shafts 12 a and 12 b may be movedtoward one another, e.g., to the first approximated position, to pivotjaw members 110, 120 about pivot pin 150 toward the closed position tograsp tissue between tissue sealing plates 219, 229 of disposablecomponents 210, 220, of jaw members 110, 120 respectively, as shown inFIG. 13A. Shafts 12 a and 12 b may be approximated relative to oneanother to selectively engage ratchet 30 such that the user may controlthe closure force applied to tissue grasped between jaw members 110,120. Next, the user may selectively apply electrosurgical energy toelectrically-conductive tissue sealing plates 219 and 229 of jaw members110 and 120, respectively, to seal tissue grasped between jaw members110, 120.

Referring now to FIGS. 13A-13B, although shafts 12 a, 12 b have beenmoved to the first approximated position to move jaw members 110, 120 tothe closed position to grasp tissue between sealing plates 219, 229,respectively, thereof, at this point, leaf spring 281 remains disposedin the at-rest position, cam pin 284 remains disposed at the proximalends 15 a, 267 of cam slots 13 a, 266, actuator arms 262 remain disposedin the un-actuated position, and knife blade 261 remains disposed in theinitial position.

When it is desired to cut tissue grasped between jaw members 110, 120,shafts 12 a, 12 b are moved closer to one another, e.g., toward thesecond approximated position. As shafts 12 a, 12 b are moved toward thesecond approximated position, the ratchet 30 is moved to anover-extended position wherein the teeth of ratchet 30 no longer engageone another, e.g., such that shaft members 12 a, 12 b are thereaftercontinuously movable to the second approximated position. Eventually,upon translation of shafts 12 a, 12 b toward the second approximatedposition, shaft 12 b contacts the arch-shaped leaf spring 281. Uponfurther approximation of shafts 12 a, 12 b, shaft 12 b urges leaf spring281 from the arch-shaped configuration to a relatively linear-shapedconfiguration. In other words, shaft 12 b urges the apex of arch-shapedleaf spring 281 toward shaft 12 a such that the distal end 282 of leafspring 281 and, thus, cam pin 284 which is coupled thereto, are urgeddistally.

As cam pin 284 is urged distally through cam slots 13 a, 266, of shaft12 a and actuator arms 262, respectively, actuator arms 262 are rotatedabout pivot pin 150 relative to shaft 12 a and end effector assembly 100from the un-actuated position (FIG. 13A) to the actuated position (FIG.14A), due to the angled, or mis-aligned positioning of cam slots 266 ofactuator arms 262 relative to cam slots 13 a of shaft 12 a. As shown inFIGS. 14A-14B, as actuator arms 262 are rotated about pivot pin 150 tothe actuated position, pivot pin 150 is rotated due to themechanical-keying engagement therebetween and, in turn, knife blade 261is rotated due to the mechanical-keying engagement between knife blade261 and pivot pin 150. More specifically, as best shown in FIG. 14B,knife blade 261 is rotated from the initial position within jaw member110 to the extended position, wherein knife blade 261 extends betweenjaw members 110, 120, e.g., through blade slot 116 defined within jawframe 112, elongated aperture 214 defined within jaw housing 211, bladechannel 216 defined within insulator 215, and blade channel 235 oftissue sealing plate 219, to cut tissue grasped therebetween.Ultimately, once shafts 12 a, 12 b reach the second approximatedposition, knife blade 261 may be configured to extend completely throughtissue and into blade channel 237 defined within tissue sealing plate229 of jaw member 120.

Once tissue has been grasped, sealed and/or divided, jaw members 110,120 may be returned to the open position, e.g., via moving shafts 12 a,12 b back to the spaced-apart position, to release the sealed anddivided tissue. As shafts 12 a, 12 b are returned to the spaced-apartposition, shaft 12 b is moved apart from leaf spring 281, allowing leafspring 281 to return to its at-rest position. As leaf spring 281 isreturned to its at-rest position, cam pin 284 is translated proximallysuch that actuator arms 262 are rotated back to the un-actuated positionand such that knife blade 261 is returned to the initial position. Oncejaw members 110, 120 have been moved to the open position to releasetissue, forceps 10 may be removed from the surgical site.

At the completion of the surgical procedure, disposable components 210,220 may be removed from jaw frames 112, 122 of jaw members 110, 120,respectively, and discarded. Additionally, forceps 10 may be furtherdisassembled, e.g., knife assembly 260 may be removed and discarded,such that the remaining components of forceps 10 may be sterilized forreuse. Thereafter, forceps 10 may be reassembled with new disposablecomponents 210, 220 and a new knife assembly 260 for subsequent use.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. While several embodiments of the disclosure have been shownin the drawings, it is not intended that the disclosure be limitedthereto, as it is intended that the disclosure be as broad in scope asthe art will allow and that the specification be read likewise.Therefore, the above description should not be construed as limiting,but merely as exemplifications of particular embodiments. Those skilledin the art will envision other modifications within the scope and spiritof the claims appended hereto.

What is claimed is:
 1. A forceps, comprising: a pair of shaft memberseach having a jaw member disposed at a distal end thereof, at least oneof the shaft members moveable relative to the other about a pivot pinbetween a spaced-apart position and a first approximated position tomove the jaw members between an open position and a closed position; anda knife assembly, the knife assembly including: a knife blademechanically keyed to the pivot pin and moveable between an initialposition, wherein the knife blade is disposed within one of the jawmembers, and an extended position, wherein the knife blade extends atleast partially between the jaw members; and at least one actuator armmechanically keyed to the pivot pin and extending therefrom, the atleast one actuator arm moveable between an un-actuated position and anactuated position to rotate the pivot pin relative to the jaw members tomove the knife blade between the initial position and the extendedposition.
 2. The forceps according to claim 1, wherein the at least oneactuator arm is coupled to a spring at an end thereof, the springmoveable between an at-rest position and an extended position to movethe at least one actuator arm between the un-actuated position and theactuated position.
 3. The forceps according to claim 2, wherein thespring is moved from the at-rest position to the extended position uponmovement of the shaft members to a second approximated position.
 4. Theforceps according to claim 2, wherein the spring is engaged to one ofthe shaft members at an end thereof and to the at least one actuator armat an opposite end thereof.
 5. The forceps according to claim 4, furthercomprising: a first cam slot defined within one of the shaft members; asecond cam slot defined within the at least one actuator arm; and a campin disposed through the first cam slot, the second cam slot, andcoupled to the distal end of the spring, such that, upon movement of theshaft members to the second approximated position, the spring is movedfrom the at-rest position to the extended position to translate the campin along the first and second cam slots, thereby moving the at leastone actuator arm to the actuated position.
 6. The forceps according toclaim 5, wherein, upon movement of the shaft members to the secondapproximated position, one of the shaft members contacts the spring andurges the spring to move from the at-rest position to the extendedposition.
 7. The forceps according to claim 1, wherein at least one ofthe jaw members includes: a jaw frame fixedly engaged to the respectiveshaft member; and a disposable jaw housing releasably engageable withthe jaw frame.
 8. The forceps according to claim 7, further comprising aseal plate releasably engaged to the jaw housing.
 9. The forcepsaccording to claim 8, wherein the seal plate includes alongitudinally-extending blade channel defined at least partiallytherethrough, the blade channel configured to permit passage of theknife blade therethrough upon movement of the knife blade from theinitial position to the extended position.
 10. The forceps according toclaim 7, wherein the jaw housing includes at least one engagementfeature configured to releasably engage a complementary engagementfeature defined within the jaw frame.
 11. The forceps according to claim1, wherein the shaft members, the pivot pin, and the knife assembly arereleasably engaged to one another.
 12. A method of assembling a forceps,comprising the steps of: providing a pair of shaft members, each shaftmember having a jaw member disposed at a distal end thereof; providing apivot pin including first and second mechanical keying features;providing a knife assembly including: a knife blade including a firstcomplementary mechanical keying feature; and at least one actuator armincluding a second complementary mechanical keying feature; pivotablycoupling the pivot pin to the shaft members such that the shaft membersare movable between a spaced-apart position and a first approximatedposition to move the jaw members between an open position and a closedposition; engaging the first mechanical keying feature of the pivot pinwith the first complementary mechanical keying feature of the knifeblade; and engaging the second mechanically keying feature of the pivotpin with the second complementary mechanical keying feature of the atleast one actuator arm; wherein, movement of the at least one actuatorarm from an un-actuated position to an actuated position rotates thepivot pin relative to the jaw members to move the knife blade from aninitial position, wherein the knife blade is disposed within one of thejaw members, to an extended position, wherein the knife blade isextended between the jaw members.
 13. The method according to claim 12,wherein at least one of the jaw members includes: a jaw frame fixedlyengaged to the respective shaft member; and a disposable jaw housingreleasably engageable with the jaw frame.
 14. The method according toclaim 13, further comprising the step of releasably engaging thedisposable jaw housing to the jaw frame.
 15. The method according toclaim 12, further comprising the step of coupling a proximal end of theat least one actuator arm to a proximal end of one of the shaft members.16. The method according to claim 15, wherein the step of coupling theproximal end of the at least one actuator arm to the proximal end of oneof the shaft members includes: inserting a cam pin through a first camslot defined within one of the shaft members; and inserting the cam pinthrough a second cam slot defined within the at least one actuator arm,such that, upon movement of the shaft members to a second approximatedposition, the cam pin is translated along the first and second camslots, thereby moving the at least one actuator arm from the un-actuatedposition to the actuated position.
 17. The method according to claim 15,further comprising the steps of: providing a spring having a proximalend and a distal end; coupling the cam pin to the distal end of thespring; coupling the proximal end of the spring to a proximal end of oneof the shaft members, the spring being moveable from an at-rest positionto an extended position upon movement of the shaft members to the secondapproximated position to move the at least one actuator arm from theun-actuated position to the actuated position.
 18. A method ofassembling a jaw member including a jaw frame, a jaw housing, aninsulator, and an electrically-conductive seal plate, the methodcomprising the steps of: positioning the seal plate about the insulator;slidably positioning the jaw housing about the seal plate and theinsulator such that the jaw housing, the seal plate, and the insulatorare retained in fixed relation relative to one another; and releasablyengaging the jaw housing to the jaw frame to retain the jaw housing, theseal plate, the insulator, and the jaw frame in fixed relation relativeto one another.
 19. The method according to claim 18, wherein jawhousing includes a track defined therein and wherein the seal plateincludes a pair of wings configured to slidably engage the track of thejaw housing to secure the seal plate, the jaw housing, and the insulatorto one another.
 20. The method according to claim 18, wherein theinsulator is formed at least partially from a resiliently compressiblematerial, the insulator configured to be compressed from an initialstate to a compressed state upon positioning of the jaw housing aboutthe seal plate and the insulator such that a bias of the insulator backtoward the initial state frictionally retains the jaw housing, the sealplate, and the insulator in fixed relation relative to one another.